Electrolytic process of producing copper.



M. PERREUR-LLOYD.

ELECTROLYTIC PROCESS OF PBODUCING COPPER.

APPLICATION FILED MAE. 28,1912.

Patented Mar. 23, 1915.

2 SHEETS-SHEET 1.

M. PERREUR-LLOYD.

ELECTROLYTIC PROCESS OF PRODUCING COPPER. APPLICATION FILED MAR.28,1912,

1, 1 33,059. Patented Mar. 23, 1915.

2 SHEETS-SHEET 2.

se u q MARCEL PERREUR-LLOYD, OF BUULOGNE-SUR-SEINE, FRANCE.

ELECTROLYTIC PROCESS OF ZPRQDUCING COPPER.

Specification of Letters Patent.

Patented Mar. 23, 1915,,

Application filed March 28; 1912. Serial No. 686,826.

To all whom it may concern Be it known that I, MARGEL PERREUR- LLOYD, a citizen of the Republic of France,

' residing in Boulogne sur- Seine, Seine,

France,'have invented certain new and useful Improvements in Electrolytic Processes o frroducing" Copper, of which the following is aspecification.

with iron in the state of ferric salts.

The improved process is applicable to all solutions of sulfates, chlorids and other salts of copper, but reference will be made more particularly in the following description to sulfstesolutions by way of example.

' Nhen an impure solution of a copper salt issubjectedto the action of an electric curtion, with a low voltage, such as .6

renhitsstrength decreases rapidly at the surface which is in contact with the cathode, so that it is necessary to increase the voltage in order to continue the decomposition of W 4 Forinstsncc' an electroniotb l foitcepf 1.26'volts is sulli'cient to decompose al sol ution ofoopper's but when the copper content decreases the voltage rapidly rises to 1.5 volts With a. resulting decomposition of the Water of the solution. The yield of the process then decreases considerably, and furthermore the increasing oxygen s r-i3- ing from the decomposition of the water, rapidly destroys the anodes.

[It has been proposed to employ sulfur diqxid. in solution in the electroly e es a dcpolarizing agent which combines a'nodewith the radical SO resulting from the decomposition of the copper sulfate, thus facilitating the decomposition of the soluor .7 of :1 volt instead of 1.26 volts which is necest is Q ssry, as stated above, when there is no sulfur dioxid in solution.

The presence-of sulfur dioXid in the solu tion; has the 'additional'sdvantage of preventingthe harmful action of theferric salts contained in the impure solution on the cop per which is deposited on the cathode, it being well known that the ferric salts dissolve a part of the copper during its formation,

- so that the yield of the process is very small.

This disadvantage does not exist-"'if'the elec ttolyte contains sulfur diox'id'in solution,

, since the-latter reduces the ferric salts into at the ferrous salts, which have no action upon copper. These advantages, due to the presence of the sulfur dioxid, are not sufiioient to make the process practicable, because the solution of the copper salt becomes gradually weaker at the parts which are in con tact with the cathode, so that a continually increasing voltage will be necessary, which rapidly becomes high enough to cause the decomposition of the water. 'T he oxyger as thus produced, is liberated at the anode and forms with the dissolved sulfur dioxid, sulfuric acid, while the hydrogen resulting from the (lQCOl'DPOSlhlOIl of the water is libeluted at the cathode, forming with the sul-- furousfacid, i. e. sulfur die-Kid in solution, hypo-sulfurous acid.

in,so,+sn:s (Gill) -rno.

The hyp'o-sulfurous acid is itself decomposed by the hydrogen produced by the decomposition of the water, and forms sul fureted hydrogen in contact with the oathode, on which it precipitates hlcclc copper sulfidl The products of the electrolysis which are formed. ell the cathodethen become gradually impure and. impregnated with copper sulfios .lt will be understood from the prec ding explanations that if the sulfur dioXid is used as a reducing means for the ferric salts which are -(letrin'ientul in their dissolving action on the copper, so as to enable the voltage to be reduced due to the depolarizing action, the use of sulfur dioxid at the same time necessitates an increase in the voltage due to the solution becon'iing' grod-- Kelly exhausted at the surface which in contact with the cathode this increased voltage causing the water to be decomposed, which giyes rise to the production of black copper sulfid. This disadvantage is due to the action of the sulfur dioxid under the conditions in which it has been used up to L value, and this is an absolutely necessary condition, as has been explained above in order that there shall be no decomposition of the water and formation of black copper sulfid. Secondly, the agitation of the elec trolyte renews continuously the layer of sulfur dioXid which is in contact with the anodes; the depolarization by the sulfur dioxid is therefore insured, which again permits of the voltage being decreased, while at the same time the depolarization thus produccd keeps the anodes in perfect condition whether theyware composed of lead or of carbon.

The improved process for the production of copper by electrolysis, which permits of the treatment of impure solutions, such as are produced by the lixiviation of ores, is thus characterized by the combination of the action of the sulfur dioxid in solution in the electrolyte (which reduces the ferric salts and prevents them attacking the copper deposited, at the same time insuring the depolarization and the diminution of the voltage) and the agitatation of the electrolyte which effects the constant renewal of the electrolyte in contact with the cathode, obviates its impoverishment, and consequently the increase in the voltage, so that the latter is always maintained sufficiently low to prevent decomposition of the water and formation of black copper sulfid. This process therefore. enables the advantages which may be secured by the use of sulfur dioxid in solution in the electrolyte to be obtained without its disadvantages. The combination of the action of the sulfur dioxid and the agitation gives aresult which it is impossible to obtain by agitation alone, as has previously also been proposed, but without the use of the sulfur dioxid, so that the harmful effect of the ferric salts was not avoided.

With sullicient agitation of the electrolytc, keeping the sulfur .dioxid in solution, it is possible to employ a current of 100 ampcrcs or more per square meter of cathode area and to extract copper from the most impure solutions up to 0.1% while obtaining good deposits of pure and coherent copper. lt should be noticed that this electrolytic process insures the production on the spot of all the acid necessary for the lixiviation of the ores. In fact, if we take for example the treatment of a solution of copper sulfate, the electrolytic decomposition results in depositing at the cathode a molecule of copper while the radical S0, is liberated at the anode, where it combines with the sulfurous acid in solution in the electrolyte as has been explained above, and thus forms two molecules of sulfuric acid. This depolarization is also facilitated by the salts of iron which are present in the solution under treatment; the ferrous salts being transformed at the anode into ferric salts by the radical S0 these ferric salts being in turn brought back to the condition of ferrous salts by the sulfurous acid with a liberation of two molecules of sulfuric acid. It is known that the sulfurous acid used for the treatment may advantageously be obtained from the roasting of the ores used.

The agitation of the electrolyte may be produced in different ways; by the movementof the electrodes or by the movement of the electrolyte. It is difficult to produce the latter easily and without inconvenience otherwise than by a blast of air which. wou d have the effect of expelling all the sulfurous acid contained in the bath; and it is preferable to impart a movement to the electrolyte by means of the electrodes themselves. As, however, the weight of the electrodes is considerable, it is preferable only to put either the anodes or the cathodes in motion. The cathodes could be rendered rotatable by forming them of cylinders or disks secured to a shaft, but such an arrangement is costly and their effective surf ace is very small compared with the space occupied- The simplest and most advantageous arrangement consists in using stationary cathodes arranged on each side of the anodes, the latter, which are of lead or carbon, being constructed in two parts, one oflwhich is stationary and the other movab e.

In order that the nature of the invention may be clearly understood a preferred form of construction will now be described by way of example in reference to the drawing. Figure 1 is a transversal section and Fig. is a longitudinal section. The electrolytic apparatus comprises a tank of wood or other suitable material in which are supported a number of rectangular or square electrodes, the anodes A B and cathodes C being arranged alternately. Each of the anodes comprises a rotating center portion in the form of a disk B, the. remainder A of the anode being stationary and being suspended from a suitable supporting bar a secured to the top of the tank, the supporting bars a being also connected to the positive terminal 771; of the apparatus. The stationary portions of the anodes are held in position at their base by means of strips of ebonite or other suitable material The disks B constituting transport of the acid.

attached to the disk. The cathodes are similarly supported in the ebonite strips D at the base of the tank and are suspended at their upper edges by means of hooks e secured to a horizontal bar n forming the negative terminal of the apparatus. The cathodes, which may be of copper or any other suitable metal, can be arranged in very close proximity to the movable anodes so as to obtain a maximum effective surface for a predetermined bulk. The movement of the rotating disks is transmitted to the electrolyte so that its whole mass is properly agitated and circulated between the electrodes. The tank is preferably provided with a cover in order to avoid loss of sulfurous acid by evaporation. The anodes are, preferably composed of lead but if; it is desired to economize electromotive force, carbon anodes similarly arranged may be employed.

It is found in practice that with the improved apparatus the amount of electric energy required per kilogram of copper deposited may be reduced to less than 1 kilowatt hour. In the operation of the apparatus the rapid movement of a portion of the anodes and the agitation of theielectrolyte resulting therefrom are favorable to the crepolarization and consequently the production of sulfuric acid which is ultimately utilized for the solution of the copper contained in the ores and also to replace that which is lost by neutralization during the lixiviation of the carbonates or of certain oxids contained in the ores.

The production by electrical means and on the spot of the sulfuric acid is of the greatest importance since it permits of employing a liquid process and electrolyzes the copper ore at the mine itself, thus obviating The latter is evidently produced at a very low cost since it is manufactured in the electrolytic apparatus itself by means of the sulfurous acid necessary for depolarization, this sulfurous acid itself being obtained by the roasting of the ores when they are of the sulfid variety or from the roasting of the pyrites when the ores to be treated are oxids or carbonates of copper.

The apparatus herein set forth is claimed in my divisional application, Serial No. 723,495, filed Oct. 2, 1912.

Claims:

1. A process for the production of a metal by the electrolysis of impure solutions of salts of the metal, wherein sulfur dioxid is added to the electrolyte to be decomposed,

and an active vertical circulation is pro duced in the electrolyte whereby the den sity of the bath is rendered uniform and the film of. electrolyte in. contact with the anodes of the apparatus is continually renewed.

2. A process for the production of a metal by electrolysis of an electrolyte yielding the metal, comprising adding sulfur dioxid to the electrolyte to be decomposed, and actively vertically circulating the electrolyte containing the dissolved sulfur dioxid in such manner that fresh portions of the electrolyte are brought into contact with the electrodes of the ap aratus, and the density of the bath is ren cred uniform.

3. A process for the production of a metal by electrolysis of an electrolyte yielding the metal, comprising adding sulfur dioxid to the electrolyte to be decomposed, and ac tively vertically circulating the electrolyte containing the dissolved sulfur dioxid by movement of an electrode of the apparatus, in such manner that fresh portions of. 1 electrolyte are brought into contact the electrodes of the apparatus and the den 51 sity of the bath is rendered uniform.

4. A process for the production of a moral by electrolysis of an electrolyte yielding metal, comprising adding sulfur dioxid. to

the electrolyte to be decomposed, and are 3 tively vertically circulating the electrotvt-zz containing the dissolved sulfur dioxid b movement of the anode in such manner that fresh portions of the electrolyte are hmuglw;

into contact with the electrodes of the a1 1 paratus, and the density of the bath is zendered uniform.

5. A process for the production of a mera by electrolysis, of an electroi yieldi the metal, comprising adding sulfur iii to the electrolyte to be decomposed, tating an electrode on a horizontal axis par allel to adjacent electrodes, to produce an, active Vertical circulation of the elect/r1? and to render the density of the electr: uniform.

In Witness whereof, I have heronnm signed my name in the presence of two scribing witnesses.

MARCEL PERREUR-LLOYD.

Witnesses Lucian MEMMINGER,

BARDY. 

